Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1991-02-05
1993-03-02
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
562400, 562501, 562504, 562601, C07C 6112
Patent
active
051911159
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a process for the preparation of carboxylic acids wherein the carbon atom in alpha of the carboxylic group is a tertiary carbon atom, the process consisting of reaction the corresponding alkanes with formiates.
The Koch synthesis of branched carboxylic acids is carried out by the reaction of olefins with carbon monoxide and water, catalyzed by inorganic acids, such as sulfuric acid or phosphoric acid, at moderate temperatures and pressures: ##STR1## wherein: ##STR2## generally represents isobutene or an olefin with C.sub.5 -C.sub.10.
The reaction of Koch and Haaf is a variant at atmospheric pressure of the Koch reaction wherein carbon monoxide is introduced by the decomposition of formic acid and wherein the derivative to be carbonylated may be an olefin or an equivalent functional derivative (F. Falbe, "New syntheses with carbon monoxide", Springer, Weinheim, 1980): ##STR3## wherein: ##STR4## generally represents isobutene or an olefin with C.sub.5 -C.sub.10. Y is a hydroxyl, halogen or alkoxyl radical.
Another method of the direct synthesis of carboxylic esters is also known by the reaction of an olefin and an alkyl formiate in the presence of an inorganic acid, such as sulfuric acid (EP-A-0 219 948; EP-A-0 092 350; EP-A-0 106 656): ##STR5## wherein: ##STR6## generally represents isobutene or an olefin with C.sub.5 -C.sub.10. R preferably is a methyl group or a primary alkyl group with C.sub.2 -C.sub.10.
It is equally possible, according to the work of Haaf and Koch, to prepare at atmospheric pressure carboxylic acids from alkanes, by using formic acid as the source of carbon monoxide and a functional derivative RY, which serves to activate the alkane to be carbonylated: ##STR7## wherein: R' represents an isoalkane and
The applicant has now discovered that it is possible to obtain carboxylic acids of the type indicated above by the direct reaction of an alkane with a formiate, without it being necessary to add formic acid to the reaction medium.
The advantage of the process according to the invention is that it makes it possible to obtain carboxylic acids of the aforementioned type by carboxylation at the ambient temperature and pressure. Furthermore, this reaction may be carried out by means of alkanes or alkane fractions, the chemical conversion of which is difficult. Finally, an additional advantage of the process is due to the fact that it makes possible the use of formiates (which may be obtained industrially by capturing carbon monoxide in the gaseous effluents of certain industrial processes) serving as the liquid transport medium of carbon monoxide and as an alkane activator.
The first object of the present invention is thus a process for the preparation of a carboxylic acid represented by the Formula (I): cycloalkyl radical with one or several rings, attached or not, and optionally substituted by at least one alkyl radical, with the carbon in alpha of the carbonyl group being a tertiary carbon atom, characterized in that a branched or cyclic alkane of Formula (II): one or several rings, attached or not, and optionally substituted by at least one alkyl radical, the carbon atom in alpha of the hydrogen atom being a tertiary atom or a secondary atom capable of being rearranged in the course of the reaction into a tertiary atom, with a formiate of Formula (III): ##STR8## wherein R.sup.2, R.sup.3 and R.sup.4 each independently represent a hydrogen atom or an alkyl radical, with the triple condition that R.sup.2, R.sup.3 and R.sup.4 do not represent simultaneously a hydrogen atom, that the compound (III) lead in the reaction medium, directly, or after rearrangement, to a stable cation R.sup.2, R.sup.3, R.sup.4 C.sup.4, and that the alkane formed from the cation may be readily eliminated from the reaction medium.
The reaction scheme is thus the following: ##STR9##
In this novel reaction the formiate of Formula (III) decomposes in the presence of an acid, to yield carbon monoxide and a cation R.sup.2 R.sup.3 R.sup.4 C.sup.4. ##STR10##
With respect to the carboxylation reac
REFERENCES:
patent: 4002674 (1977-01-01), Inamoto
Gallo Roger
Jalal Rachid
Lazzeri Veronique
Atochem
Shippen Michael L.
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